Cupped item, is it a coin? [решено]

The concave part of this item has writing. I can identify “EXTRA” . The convex side seems to  be blank.

 There was similar on here a few years ago - the EXTRA is part of the 

lettering on the back of a button. 

 The word after EXTRA looked like RICH, and indeed now found this … 

TREBLE STANDD EXTRA RICH 

https://www.detectorprospector.com/forums/topic/6943-button-help-please/ 

 On yours the loop has broken off, which is probably how it got separated from the coat it was on. 

 Yours is called a dome button. 

Another with lettering … 

… a small depressed R&W. ROBINSON * EXTRA RICH * backmark. 

https://www.angelfire.com/nj4/keemakoo/te.html 

 Lastly, what other lettering can you see inside - 

as the camera focused outside the item. 

 Seems quite a few manufacturers used EXTRA RICH on their buttons … 

https://metaldetectingforum.com/showthread.php?t=75566 

https://metaldetectingforum.com/showthread.php?t=234366 

 and so on … 

Definitely that button. Thanks. Just weird that writing is on the inside where normally no one would ever see it.